For the crumble, combine all ingredients in a mixing bowl. Set aside.
To make the filling, in a large bowl, combine all of the ingredients for the filling. Using the back of your spoon, crush about 20 percent of the blueberries so the juice mixes with the arrowroot starch and thickens the filling.
To make the pie, preheat the oven to 350 degrees.
Fill the crust with the berry mixture, spreading evenly, and top with the crumble. Place on a parchment paper-lined baking sheet and bake until the filling starts to bubble, one hour to one hour and twenty minutes, depending on your oven. Remove and cool on a wire rack.